Photoluminescence in semiconductor structures based on butyl-substituted erbium phthalocyanine complexes
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PHOUS, VITREOUS, POROUS, ORGANIC, AND MICROCRYSTALLINE SEMICONDUCTORS; SEMICONDUCTOR COMPOSITES
Photoluminescence in Semiconductor Structures Based on Butyl-Substituted Erbium Phthalocyanine Complexes I. A. Belogorokhov^, Yu. V. Ryabchikov, E. V. Tikhonov, V. E. Pushkarev, M. O. Breusova, L. G. Tomilova, and D. R. Khokhlov Moscow State University, Moscow, 119899 Russia ^e-mail: [email protected] Submitted July 3, 2007; accepted for publication August 21, 2007
Abstract—The study is concerned with the luminescence properties of ensembles of semiconductor structures containing organic phthalocyanine molecules with erbium ions as complexing agents. The photoluminescence spectra of the structures of the type of erbium monophthalocyanine, bisphthalocyanine, and triphthalocyanine are recorded. The photoluminescence peaks are detected at the wavelengths 888, 760, and 708 nm (and photon energies 1.4, 1.6, and 1.75 eV) corresponding to electronic transitions within the organic complexes. It is found that, when a metal complexing agent is introduced into the molecular structure of the ligand, the 708 nm luminescence peak becomes unobservable. It is shown that, in the bisphthalocyanine samples, the photoluminescence signal corresponding to transitions from the 4F9/2 level of erbium ions is enhanced. PACS numbers: 78.55.Kz DOI: 10.1134/S1063782608030147
1. INTRODUCTION Organic semiconductor structures find expanding applications in the problems of present-day microelectronics [1]. In particular, it is known that structures composed of large protein molecules feature a rather high mobility of electrons [2]. The basic advantage of organic materials is the simplicity of their production from the derivatives of organic compounds widely occurring in nature. The technologies of synthesizing organic molecules do not require large expenditures of energy or complex instrumentations, such as are used, e.g., in molecular beam epitaxy, gas phase epitaxy, hydride epitaxy, photolithography, or anisotropic chemical etching [3, 4]. It should be also noted that many organic structures exhibiting semiconductor properties occur in nature in a ready form [5]. For example, the structures of magnesium porphyrinates reveal themselves as chlorophyll molecules in the cells of any plants, and erythrocytes in blood corpuscles of mammals are the compound of porphyrin with an iron atom. Phthalocyanine is a synthetic analogue of porphyrin. The basic feature of phthalocyanines is their stability to thermal decomposition [2]. To the advantages of organic structures can be added their selective optical properties that can be varied by modifying the structure of molecules during synthesis [6, 7]. In [8–10], it was shown that phthalocyanine molecules exhibit three peaks of absorption of optical radiation in the visible and ultraviolet spectral regions and
can show two distinguishable photoluminescence (PL) peaks in the range between 900 and 1100 nm. Current achievements in the chemistry of phthalocyanines make it possible to synthesize three-dimensional-struct
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